Propeller



L. T. FREDERICK.

PROPELLER.

APPLICATION FILED DEC-30, I918.

Patented Feb. 14, 1922.

ENVENTOR 2' Frederick WITNESSES ATTORNEY UNITED STATES PATEN roFnc I LOUIS r. rnnnnmcx, or 'WILKINSBURG, HOUSE ELECTRIC a MANUFACTURING vsnra- PENNSYLVANIA ASSIGNOR TO .WESTING- COMPANY, A. CQRPORATIQN OF PENNSYL- I PROIELLER.

To all whom it may concern:

Beit known that I, LOUIS,T. FREDERICK, a citizen of the United States, and a resident of Wilkinsbur in the county of Allegheny and State of ennsylvaniahave invented a new and useful Improvement in Propellers, of which the'followlng is a specification;

My invention relatesto air screws or propellers foraircraft, and it has for its primary object the provision of a composite propeller possessing certain desirable characteristics.

More particularly my present invention relates, to a propeller havlng a working body portion comprising superlmposed layers of fibrous sheet material, im regnated with a .hardened binder, in whic the layers are preferably disposed in planes substantially parallel to the faces of the hub. One of the objects of this invention consists in providing. a propeller of this character in the form of a hollow body, of the above indicated composition, enclosing a permanent core ofwood,

cork or other suitable material whereby the wei ht of the propeller may be decreased. eret'ofore, propellers'formed entirely of wood have been undesirable because of their warping, under climatic changes, and their likelihood to splinter and pit during use. Satisfactory ropellerscomposed solely of fibrous material and a hardened binder have been made which are not subject to these criticisms but such propellers are," under presentconditions, more. expensive because of the cost of materials. By practising my present invention, I provide a propeller havmg an mexppnsive inner body portion or core covered y an outer casing or shell of a material which will efiectively and satisfactorily withstand all'operating conditions.

Another object which I have in view is the provision of a simple and rapid means of assembling and forming a propeller of this character.

With these and other objects in view, my invention will be more fully described, illustrated in the drawin in the several views of which correspon ing numerals indicate. like parts, and then particularly pointed out in the claims. Q I Fig. 1 is affront elevation of apropeller constructed in accordance with my iIIVGIl-J tion-fiFig. 2 is a top plan view of the propeller, the core .being shown in broken lines,: Fig. 8 is a diagrammatic section illustrating constituting the propeller.

Specification of Letters Patent. I Patented Feb; 14, 1922. Application filed December so, 1918. Serial in. 268,958.

the method of assembling the component parts of the taken substantlallyon the line III-III of Fig; 2, and-Figs. 4 and 5 are plan views ofproperly shaped layers of fibrous material which may be employed in. the propeller construction and which, in practice, will occupy substantially the positions indicated by the l[1 nes 2.IV, V and V-V respectively of 1 other pre erred form. This fibrous material may preferably be impregnated with a suitable blnder before it is applied to the core although this impregnation maybe accompllshed afterJ the propeller is assembled, if desired. The assembled propeller may then propeller, the section being.

be cured in any suitable manner, usually in a V mold, in such away as to permanently arden the binder and compact the mater More particularly, I prefer to follow a rocess disclosed in a co ndingapplication filed by D. A. Dickey, ec..30, 1918, Serial No. 268,949 and assigned tothe Westinghouse Electric &'Manufacturing Company, in which fibrous sheet material, such as duck or other woven fabric, paper orcotton battin is im regnated with a suitable binder,

suc as a p enolic condensation product, and

dried to drive off the solvent employed in I.

the binder without afiecting the. roperties of the binder. This sheet materia as fully disclosed in the above-referred-to a-p lication, is then cut into layers of suitable s apes and sizes so that, when the layers are superimposed, in proper successive positions relative to each other, a substantially propellersha (1 body will result. I

en practising my invention, I

the-layers 1 in the same manneras t t diewhen the layers are assembled, a space 0 proper size and shape for the reception of a core 3 may be provided. In assembling my propeller. 4 the. various layers 1 are superimposed in roper positions relative to rovide 190 closed in the above-referred to application but cut or otherwise. form openings '2 incertain of the layers in such manner'that? completely enclosing the core, after which the assembled bod 1S compressed and cured. If the binder emp oyed is a phenolic condensation product, the curing may best be performed by subjecting the assembled-body to heat and pressure, in a mold of proper design, to strongly compact the material and transform the binder to its solid and substantially insoluble and infusible state.

Obviously, a propeller constructed in accordance with my invention is 'as resistant to injury, under operating conditions, as-a propeller constructed entirely of fibrous material and a binder and, at the same time, it may, under present conditions, be more economically manufactured and may, in some instances, be somewhat lighter in weight.

Although I have illustrated and'described but one method of constructing a propeller in accordance with my invention, it will be appreciated that other methods of preparing the materials, including both the core and the sheet material, and of assembling them, may be practiced without departing from the spirit of my invention. For this reason, no limitationsare to be imposed iponmy invention other than those set forth in the ing the core and formed of composite material molded thereto.

3. A propeller comprising a non-metallic core and a body of fibrous -material impreg- "nated with a hardened binder molded about the core.

4. A propeller comprising a core of wood and a body of fibrous sheet materialimpregnated with a hardened phenolic condensation product molded about the core.

5. A propeller comprising a core and a propeller-shaped casing molded about the core and comprising superimposed layers of fibrous sheet material impregnated with a hardened binder.

6::A propeller comprising a core and a propeller-shaped casing m lded about the core and conprising superimposed layers of fibrous sheet material impregnated with a hardened binder, the sheets being disposed inplanes substantially parallel with the faces of the propeller'hub.

7. A propeller comprising a core of wood and a plurality of sheets of impregnated fibrous material superimposed upon each other and enclosing the core, the sheets being impregnated with a phenolic condensation product which has been hardened by heat and pressure.

8. The method of forming a propeller which comprises providing a non-metallic core and molding fibrous material impregnated with a binder about the core.

9. The method of forming a propeller which comprises shaping a core, cutting a binder-impregnated sheetof fibrous material into layers of such shapes and sizes that, when properly superimposed, they will form a substantially propeller-shaped body enclosing a chamber of proper shape and size to receive the core, superimposing the sheets about-the core and subjecting the body thus assembled to heat and ressure to compact the fibrous material and harden the binder.

In testimony whereof, I have hereunto subscribed my name-this 21st day of Dec'.,

LOUIS T. FREDERICK. 

